Process and apparatus for delivering carbon material to a furnace

Abstract

A process and apparatus for delivering carbon i.e., coal dust, to be combusted in a furnace is presented. The furnace is of the type having plural combustion points and may include a shaft furnace such as, for example, a blast or cupola furnace. The carbon dust is delivered in dosed quantities to each of the individual combustion points in a separate air stream which is under a predetermined pressure. The carbon (coal dust)/carrier gas (air) is delivered to each combustion point in the furnace at super critical speed, i.e., the speed of sound, the carrier gas having a relatively high proportion of solid material therein. The actual quantity of carbon material delivered to each combustion point is directly detected and monitored as a consequence of volumetric measurement and is appropriately corrected by means of a secondary air supply when the carbon quantity either exceeds or falls below a predetermined nominal value. The apparatus of the present invention includes plural conveyor lines being connected at one end thereof to a particular combustion point. The end of the conveyor line which is connected to the combustion point comprises a nozzle which delivers the carbon/carrier gas stream at a super critical outflow speed. The diameter of the nozzle and the predetermined pressure prevailing in the conveyor line is a function of the preselected nominal quantity of carbon which is to be delivered to the furnace.

What is claimed is: 
     
       1. A process for delivering dosed quantities of carbon to separate streams of a carrier gas under a predetermined pressure, the separate carbon/carrier gas streams being delivered to a plurality of combustion points in a furnace including the steps of: supplying each separate carrier gas stream with an effectively high proportion of carbon material to create an essential constant density of carbon in said separate carrier gas stream;   detecting the quantity of carbon which is delivered to each combustion point based on a volumetric measurement of the carbon/carrier gas stream;   delivering a pre-selected, nominal quantity of said carbon to the plural combustion points of the furnace at an essentially supercritical speed; and   supplying a secondary carrier gas stream to said carbon/carrier gas stream to correct the quantity of carbon being delivered to said combustion points when said quantity is higher or lower than said pre-selected nominal quantity.   
     
     
       2. The process of claim 1 wherein the step of supplying a secondary carrier gas stream includes: increasing the quantity of said secondary carrier gas stream supplied to said carbon/carrier gas stream when said nominal quantity of carbon at least one of said combustion points is exceeded.   
     
     
       3. The process of claim 1 wherein the step of supplying a secondary carrier gas stream includes: decreasing the quantity of said secondary carrier gas stream supplied to said carbon/carrier gas stream when said nominal quantity of carbon at at least one of said combustion points is diminished.   
     
     
       4. The process of claims 1, 2 or 3 including the step of: increasing the pressure in said carbon/carrier gas stream when said nominal quantity of carbon at at least one of said plural combustion points is diminished.   
     
     
       5. The process of claims 1, 2 or 3 including the step of: decreasing the pressure in said carbon/carrier gas stream when said nominal quantity of carbon at at least one of said plural combustion points is exceeded.   
     
     
       6. The process of claims 1, 2 or 3 wherein said step of detecting the quantity of carbon delivered to each combustion point includes: measuring the time which elapses when a quantity of said carbon supplied to said carrier gas flows between a pair of detectors in a pressurized vessel, the space between said detectors defining a preselected volume.   
     
     
       7. The process of claim 1 wherein: said effectively high proportion of carbon material is 50 Kg of carbon per Kg of carrier gas.   
     
     
       8. The process of claims 1 or 7 wherein: said carbon is coal dust.   
     
     
       9. The process of claims 1 or 7 wherein: said carrier gas is air.   
     
     
       10. The process of claim 1 wherein: said furnace is a shaft furnace.   
     
     
       11. The process of claim 10 wherein: said shaft furnace is selected from the group consisting of blast furnaces and cupola furnaces.   
     
     
       12. An apparatus for delivering dosed quantities of carbon to separate streams of a carrier gas under a predetermined pressure, the carbon/carrier gas streams being delivered to a plurality of combustion points in a furnace including: means for supplying the carrier gas with an effectively high proportion of carbon material to create an essentially constant density of carbon in said carrier gas;   means for detecting the quantity of carbon which is delivered to each combustion point, based on a volumetric measurement of the carbon/carrier gas stream;   means for delivering a pre-selected, nominal quantity of said carbon to the plural combustion points of the furnace at an essentially supercritical speed and   means for supplying a secondary carrier gas stream to said carbon/carrier gas stream to correct the quantity of carbon being delivered to said combustion points when said quantity is higher or lower than said pre-selected nominal quantity.   
     
     
       13. The apparatus of claim 12 wherein the means for supplying a secondary carrier gas stream includes: means for increasing the quantity of said secondary carrier gas stream supplied to said carbon/carrier gas stream when said nominal quantity of carbon at at least one of said combustion points is exceeded.   
     
     
       14. The apparatus of claim 12 wherein the means for supplying a secondary carrier gas stream includes: means for decreasing the quantity of said secondary carrier gas stream supplied to said carbon/carrier gas stream when said nominal quantity of carbon at one of said combustion points is diminished.   
     
     
       15. The apparatus of claim 12 including: means for increasing the pressure in said carbon/carrier gas stream when said nominal quantity of carbon at at least one of said plural combustion points is diminished.   
     
     
       16. The apparatus of claim 12 including: means for decreasing the pressure in said carbon/carrier gas stream when said nominal quantity of carbon at at least one of said plural combustion points is exceeded.   
     
     
       17. The apparatus of claim 12 wherein said delivery means includes: a plurality of conveyor line means leading to each of said combustion points and leading from a pressurized vessel; and   first nozzle means, said nozzle means positioned between said conveyor line means and said combustion points, said nozzle means accelerating said carbon/carrier gas stream to said supercritical speed, and said nozzle means having a selected diameter wherein a selected quantity of carbon corresponding to said nominal quantity will flow therethrough.   
     
     
       18. The apparatus of claim 17 wherein: said nozzle means having said first diameter are interchangeable with nozzle means of other diameters in order to vary the quantity of carbon flowing therethrough.   
     
     
       19. The apparatus of claim 12 wherein said detection means comprises: a pressurized delivery vessel;   a plurality of chambers within said delivery vessel, the number of chambers being equal to the number of combustion points in said furnace, said chambers communicating with said combustion points, said carbon/carrier gas stream flowing through each of said chambers;   first detector means for detecting said carbon/carrier gas stream at a first point along each of said chambers;   said detector means for detecting said carbon/carrier as stream at a second point along each of said chambers;   timing device means wherein the quantity of carbon flowing between said first and second detector means is determined as a function of the volume between said first and second detector means.   
     
     
       20. The apparatus of claim 19 wherein: said chambers are formed by insert means having an essentially star-shaped horizontal cross-section, said insert means being positioned within said pressurized delivery vessel.   
     
     
       21. The apparatus of claim 19 wherein said delivery means includes: a plurality of conveyor line means leading to each of said combustion points and leading from said pressurized vessel; and   first nozzle means, said nozzle means positioned between said conveyor line means and said combustion points, said nozzle means accelerating said carbon/carrier gas stream to said supercritical spreed, said nozzle means having a selected diameter wherein a selected quantity of carbon corresponding to said nominal quantity will flow therethrough.   
     
     
       22. The apparatus of claim 21 wherein: said nozzle means having said first diameter are interchangeable with nozzle means of other diameters in order to vary the quantity of carbon flowing therethrough.   
     
     
       23. The apparatus of claim 17 wherein: said means for supplying said secondary gas stream communicates with each of said conveyor line means.   
     
     
       24. The apparatus of claim 19 wherein said supply means comprises: silo means capable of storing carbon therein;   means for fluidizing said carbon from said silo means;   pneumatic conveyor means, said pneumatic conveyor means pneumatically conveying said fluidized carbon between said silo means and said pressurized delivery vessel.   
     
     
       25. The apparatus of claim 24 further including: sluice vessel means communicating with said pressurized delivery vessel and said pneumatic conveyor means.   
     
     
       26. The apparatus of claim 25 further including: weighing means communicating with said sluice vessel means and said pneumatic conveyor means.   
     
     
       27. The apparatus of claim 12 wherein: said effectively high proportion of carbon material is 50 Kg of carbon per Kg of carrier gas.   
     
     
       28. The apparatus of claims 12 or 27 wherein: said carbon is coal dust.   
     
     
       29. The apparatus of claim 12 wherein: said carrier gas is air.   
     
     
       30. The apparatus of claim 12 wherein: said furnace is a shaft furnace.   
     
     
       31. The apparatus of claim 30 wherein: said shaft furnace is selected from the group consisting of blast furnaces and cupola furnaces.